double-grid (dg) analysis for BSE

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double-grid (dg) analysis for BSE

Postby sitangshu » Sun Nov 05, 2017 8:56 am

Dear Sir,

I have a small query about using double-grid (dg) analysis for BSE :

I tested an Si bulk BSE calculation on double-grid (4 4 4) by generating the Doublegrid netcdf file (ypp -m) and it worked fine.
However, when I tested the same by including the electron-phonon correction in BSE, the code complains while solving linear algebra part after kernel (used inversion solver with full perturbative). I realized that my elph was done on a lower scf and nscf grid (2 2 2) while BSE is on dg (4 4 4), so there could be a grid-mismatch. Am I correct?
Is there any trick such that elph is done on a lower scf and nscf grid say 2 2 2 but compatible with BSE done on dg, say 4 4 4?
Your answer would be very helpful for me...

Sitangshu Bhattacharya
Indian Institute of Information Technology-Allahabad
Posts: 93
Joined: Thu Jan 05, 2017 8:08 am

Re: double-grid (dg) analysis for BSE

Postby amolina » Mon Nov 06, 2017 10:17 am

Dear Sitangshu,

I think you can use the el-ph ndb.QP in a BSE calculations even the grids are different. Have you made the test?

Another option is to use an interpolation to go from 2x2x2 grid to a 4x4x4 grid but that is not yet implemented.


Alejandro Molina-S√°nchez
Physics and Materials Research Unit
Campus Limpertsberg
Université du Luxembourg
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Location: Luxembourg

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